The applicant is aware that presently in order to produce diesel from a hydrocarbon feed including a fraction having a boiling point in excess of the diesel boiling range by hydrocracking a high recirculation ratio is required thereby leading to reduced viability of the production of said diesel. The high recirculation ratio is necessitated, for amongst other reasons, by the relatively low conversions and yields to the desired products
The applicant is further aware that diesel for commercial use should preferably have good cold flow properties, a low cloud point, and a cetane number in excess of 40.
The applicant is also aware that existing hydrocracking catalysts used presently for the production of diesel from a hydrocarbon feed having a fraction having a boiling point above the diesel boiling range include commercially available amorphous Ni/W/Al2O3SiO2 catalysts as well as Ni/Mo/Al2O3SiO2 catalysts which require a high recirculation ratio as described above and amorphous Pt/Al2O3SiO2 which is a hydrocracking and dewaxing catalyst which also requires a high recirculation ratio as described above in order to produce said diesel.
The applicant is also aware of an article by S Rajagopal, J. A. Marzari and R Miranda entitled Silica-Alumina-Supported Mo Oxide Catalysts: “Genesis and Demise of Brönsted-Lewis Acidity”, which article was published in the Journal of Catalysis 151, 192-203 (1995). The entire article is incorporated in this specification by reference as if specifically reproduced here.
In the aforementioned article the authors summarise that the ratio of Brönsted to Lewis acid sites concentration (B/L) increases with SiO2 content in the support and reaches a maximum for SiO2:Al2O3 of 3:1 by weight. For alumina rich supports B/L increases continuously with MoO3 loading because of the generation of new Brönsted acid sites and decrease of Lewis acid sites, up to a theoretical maximum of 12 wt % MoO3. The article does not propose the manufacture of a catalyst of the type of this invention nor would the results set out in the article lead a man skilled in the art to conclude that a catalyst in accordance with this invention could be manufactured.
In this specification, unless the context clearly indicates to the contrary, the term conversion is used to indicate the conversion of the hydrocarbon feed to reaction products on a single pass through the reactor i.e. without recycle of reactor bottoms.
Thus, after prolonged and laborious experimentation and development work on diesel production the applicant now proposes a new catalyst and a new diesel production process in accordance with the invention.